The invention relates to a multilayer bag comprised of paper, which includes on its inside a film layer and has improved protection of the bagged goods against moisture as well as improved venting during the filling.
To attain good moisture protection of moisture-sensitive goods, paper bags frequently comprise synthetic webs as inner layers or between two paper layers. The synthetic web is either provided with apertures or needled or perforated to ensure adequate air permeability or venting during the filling of the bag.
EP 0 867 379 A1 discloses a perforated bag, in which perforation occurs through all layers of the bag. Thereby, adequate air permeability is ensured. However, there is no longer any reliable protection against moisture. Such a bag, furthermore, is no longer suitable for holding bagged goods in powder form.
WO 98/57861 discloses a multilayer paper bag suitable for holding powder-form bagged materials. The paper bag here comprises, at least in the intermediate synthetic layer, perforations in band or strip form on each broad side. To ensure adequate air permeability, these perforations or apertures must have a diameter of appropriate size. However, this reduces the strength of the bag. This is especially disadvantageous when holding goods of high weight.